Rügen chalk

The vast majority of calcium carbonate is in the form of micrometer-sized low-Mg calcite platelets known as coccoliths, which are remnants of unicellular, planktonic calcareous algae known as coccolithophores.

The calcareous algae lived around 70 million years ago in light-flooded surface water of a sea that covered northern Germany.

The silicon dioxide (SiO2) from which the flint stones were formed, originally came from single-celled plankton (radiolarians and diatoms), which lived together with the calcareous algae in the Chalk seas.

Well known deposits incude the "Rügener chalk cliffs" of the cliffed coast in the vicinity of Sassnitz (see also → Stubbenkammer, → Königsstuhl).

Through a process known as slurrying, the raw chalk was separated from the undesirable rock components such as flint (see above) and finer-grained impurities (known as Grand).

During the late 19th century, the fishing village of Sassnitz slowly developed into a centre of the chalk industry due to the deposits in Jasmund.

As a result, 17 companies with 23 chalk plants merged in 1899 to form a cartel and set limits on all member's production volumes and prices.

Some facilities, including the chalk cable car to Sassnitz harbor, were dismantled and brought to the Soviet Union as war reparations.

In the 19th and early 20th century, the chalk had to be dislodged from a steep mine face with pickaxes and transported on trucks to machines called agitators.

The chalk and water mixture, also called Kreidemilch or Kreidetrübe, was passed through separation tanks where the finer impurities, the Grand, settled out.

The previously cloudy water was drained, and the basin was filled with fresh chalk suspension, so that the fine particles could settle again.

[8] Even before 1945, chalk was shipped by train to Berlin, Bremen, Hamburg, Ruhrgebiet, Breslau and Stettin where it was used in the electrical, paint and cosmetics industries.

From the 1960s onwards, the VEB Kreidewerk Rügen was supplied with chalk in three grain types – "Malkreide 60", "Feinkreide 40" and "Mikrotherm 20".

Under the name "Three Crown Chalk" (trade name of the Swedish Pomeranian era), this was a major export item of the GDR and was delivered to 40 countries.